US5036015A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of endpoint detection during chemical/mechanical planarization of semiconductor wafers
Assignee: Round Rock Research LLC
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Filing: 1990-09-24
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Granted: 1991-07-30
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Expires: 2010-09-24
Abstract
Abstract A method and apparatus for detecting a planar endpoint on a semiconductor wafer during chemical/mechanical planarization of the wafer. The planar endpoint is detected by sensing a change in friction between the wafer and a polishing surface. This change of friction may be produced when, for instance, an oxide coating of the wafer is removed and a harder material is contracted by the polishing surface. In a preferred form of the invention, the change in friction is detected by rotating the wafer and polishing surface with electric motors and measuring current changes on one or both of the motors. This current change can then be used to produce a signal to operate control means for adjusting or stopping the process.
Inventors
- 👤 Gurtej S. Sandhu
- 👤 Laurence D. Schultz
- 👤 Trung T. Doan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 11:31
CPC Classifications
B; B24; B24B; B24B37/00; B24B37/005; B24B37/013; G; G01; G01N; G01N19/00; G01N19/02; H; H10; H10P; H10P95/00; H10P95/06; H10P95/062
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
60 words
A method for mechanically planarizing a semiconductor wafer comprising: a. holding the wafer in contact with a polishing platen in the presence of a chemical slurry; b. rotating the wafer with respect to and against the polishing platen; and c. sensing a change in friction between the wafer and the polishing platen to detect a planar endpoint on the wafer.
Claim 2
Independent Claim
60 words
A method for mechanically planarizing a semiconductor wafer comprising: a. holding the wafer in contact with a polishing platen in the presence of a chemical slurry; b. rotating the wafer with respect to and against the polishing platen; and c. sensing a change in friction between the wafer and the polishing platen to detect a planar endpoint on the wafer.
Claim 3
Dependent Claim
48 words
The process as claimed in claim 1 and further comprising: d. rotating the wafer or the polishing platen with an electric drive motor; and e. sensing a change in friction with a current meter for the drive motor which detects a change in amperage through the drive motor.
Claim 4
Dependent Claim
39 words
The process as claimed in claim 2 and wherein: sensing the planar endpoint occurs when an oxide coating on the wafer is planarized and a surface of the wafer including a different material is contacted by the polishing platen.
Claim 5
Dependent Claim
40 words
The process as claimed in claim 2 and wherein: the current meter measures a current flow to the drive motor which is equated to the torque output and to the current draw of the motor multiplied by a multiplying factor.
Claim 6
Dependent Claim
45 words
The process as claimed in claim 4 and wherein: torque (T) on the motor is equated to the force (F) between the wafer and polishing platen and to the radius (r) of the wafer from the center of the polishing platen by the formula: T=F×r.
Claim 7
Independent Claim
48 words
A method of detecting a planar endpoint on a semiconductor wafer during a mechanical planarization process comprising: a. rotating the wafer with respect to a polishing platen; and b. sensing a change in friction between the wafer and polishing platen to detect a planar endpoint on the wafer.
Claim 8
Independent Claim
48 words
A method of detecting a planar endpoint on a semiconductor wafer during a mechanical planarization process comprising: a. rotating the wafer with respect to a polishing platen; and b. sensing a change in friction between the wafer and polishing platen to detect a planar endpoint on the wafer.
Claim 9
Dependent Claim
40 words
A method as recited in claim 6 and wherein: c. the wafer is rotated with respect to the polishing platen by an electric motor; and d. sensing a change in friction is accomplished by a current meter for the motor.
Claim 10
Dependent Claim
29 words
The method as recited in claim 7 and wherein: the planar endpoint occurs when coating on the wafer is removed to expose a surface formed with a different material.
Claim 11
Dependent Claim
17 words
The method as recited in claim 8 and wherein: both the wafer and polishing platen are rotated.
Claim 12
Dependent Claim
17 words
The method as recited in claim 9 and wherein: both the wafer and polishing platen are rotated.
Claim 13
Dependent Claim
60 words
The method as recited in claim 7 and wherein: the coefficient of friction between the wafer and polishing platen is equated to the torque (T) on the motor by the equation T=F×r, where "F" is a function of the coefficient of friction and "r" is a radius from the center of the polishing platen to the center of the wafer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-07-29 | 1995-01-28 | 1995-07-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-07-29 | 1999-01-28 | 1999-07-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-07-29 | 2003-01-28 | 2003-07-30 | $7700.00 | Window Closed / Lapsed |